This invention relates to a process for forming and for the further processing of small stacks of sheet metal.
A process is known in practice for forming small stacks from an initial stack of sheet material by means of cutting, with subsequent transfer of the small stacks to a further processing station. In this process a single guillotine cutter machine is used. The latter comprises a rear table part for receiving the material to be cut and a front table part for receiving the cut material. The initial stack, which is in the shape of a right parallelepiped, is first separated into partial stacks by a plurality of cuts in a first direction perpendicular to its direction of feed. All these partial stacks, or part of these partial stacks, are subsequently subjected to further processing. For this purpose, the partial stacks to be processed are pushed, turned by 90xc2x0, from the front table part on to the rear table part for further cutting. The partial stacks are separated by at least one cut in a second direction in order to form the small stacks. The small stacks which are thus produced are fed manually, perpendicularly to the direction of feed of the guillotine cutter machine, to the further processing station, after they have previously been pushed manually slightly forward in the direction of feed, so as to be able to move them laterally past the housing of the cutting machine.
A guillotine cutter machine which can be operated according to the process described above is known from EP-A-0 056 874, for example. Processing cannot be carried out automatically with this machine, and in particular cannot be carried out automatically with respect to the cut for producing the small stacks and the transfer thereof to the further processing station. The latter can be an automatic bundling machine or a label punch, for example.
Furthermore, other apparatuses are known which enable small stacks of sheet material to be formed and further processed in an automated manner. However, these apparatuses are only suitable for carrying out defined processing steps during the formation and further processing of small stacks of sheet material, so that costly machine constructions, or at least two guillotine cutter machines, are necessary in order to cover the entire course of processing.
It is known from EP-A-0 242 763 that edge cuts which may be necessary can be made on the stack by a first guillotine cutter machine, after which the stack is present as an initial stack, and that the initial stack can also be separated into partial stacks by this machine. The partial stacks are collected on a support and are fed to the second guillotine cutter machine, which is disposed perpendicularly to the first-mentioned guillotine cutter machine. In the second cutter machine, the partial stacks are subdivided, on each cut, into small stacks which are arranged in rows. A first guide plate is disposed in front of the partial stacks with respect to the direction of feed of the material, and is thus disposed in the region of the front table part. A second guide plate can be introduced into a gap formed between the front and rear table parts, adjacent to the rear end of the front table part. The two guide plates form a transverse channel between them which receives the small stacks, which can be fed to a further processing station by means of an ejector.
Quite a costly process for cutting and for the further processing of small stacks of sheet material is known from WO 91/00168 A. This process employs a machine of complicated construction. The front table part of the machine is of two-part construction, wherein the front section of the table part is raised after separating the initial stack into partial stacks, so as thus to be able to bring a first movable guide plate, which is disposed underneath the front section of the front table part, into position in order to form small stacks in connection with the further separation of the partial stacks. Whereas the rear section of the front table part is fixedly mounted in a base frame which can be moved horizontally, the front section of the front table part is mounted in a vertically movable intermediate frame, which is mounted in the base frame and which, underneath the front section of the front table part, receives the first guide plate and elements for horizontally moving and swivelling said guide plate. The first guide plate thus forms a fixedly installed component of the front table construction. The operating procedure of this machine is costly, since due to its division into two regions the front table part is not only movable horizontally but is also movable vertically over a relatively large vertical distance.
EP-A-0 453 933 describes a process for cutting and for the further processing of small narrow stacks of sheet material. The guillotine cutter machine which is illustrated there can only produce stacks of constant dimensions as seen in the direction of feed of the material. An L-shaped element for receiving the cut small stacks is provided for this purpose. The lower arm of the L-shaped element fits under the small stacks, whilst the other arm serves as a lateral support for the stacks. The L-shaped element is mounted so that it can be moved and swivelled horizontally in a front table part of the guillotine cutter machine, but this table part is not employed for receiving the cut material. The purpose of this type of mounting of the L-shaped element is to enable the L-shaped element to be tilted away when separating the partial stacks by means of the wedge-shaped cutter and thus when forming small stacks which are initially displaced into the shape of a parallelogram, whilst the front edge of the L-shaped element remains in a plane with the table surface.
The object of the present invention is to further develop a process according to the precharacterising clause of claim 1 which, using one and the same guillotine cutter machine and a simple mode of operation, not only enables the steps to be carried out for producing partial stacks and small stacks, but which also creates conditions when this machine is used such that the small stacks can be fed automatically to further processing operations.
This object is achieved by a process according to the features of claim 1.
According to the invention, it is not until the partial stacks have been pushed back on to the rear table part, whereupon the partial stacks can rest in part on the front table part, that the first movable guide plate is installed above the front table. Before this, namely before the installation of the first guide plate, the entire table surface of the table, particularly the table surface of the front table part, is free, so that the material can be manipulated there in any desired manner, and in particularly can be turned after the cuts have been made for producing the partial stacks. It is also possible, using the guillotine cutter machine, to trim the edges of the initial stack before it is separated into partial stacks. The first movable guide plate is not installed until the front table part is no longer required for manipulating the material. Process steps which proceed automatically can be carried out by means of this guide plate, particularly in cooperation with the second movable guide plate.
Thus, the essential difference between the process according to the invention and that disclosed in WO 91/00168 A is that, according to the present invention, the first movable guide plate is installed above the front table part after the partial stack has been pushed back on to the rear table part, whilst according to the aforementioned prior art this first movable guide plate is fixedly installed underneath the front table part and is also permanently positioned underneath the front section of the front table part. Therefore, with the front section of the front table part raised, it is not possible to separate the front and rear table parts which are disposed in a plane in order to form a gap between them and in order to form the transverse channel between the two guide plates for the small stacks which are to be transported away.
According to the present invention, the partial stacks are placed in the region of the guide plate, wherein xe2x80x9cplacementxe2x80x9d is to be understood here to comprise both the placement of the guide plate with respect to the stationary partial stacks and the displacement of the partial stacks into the region of the guide plate which is already installed. In particular, the partial stacks are placed against the guide plate. This is followed by the cut for producing the small stacks, and the front and rear table parts are then moved apart in order to form the gap between them. The second movable guide plate is then placed in the region of the gap and the two stacks are fed to the further processing station through the transverse channel formed between the two guide plates. In this respect it is unimportant whether the second movable guide plate is placed from below, namely through the gap, or from the side or from above. The crucial feature is that the transverse channel is formed by the two guide plates. After the small stacks have been transported away, and in particular have been ejected, towards the further processing station, the partial stacks situated on the rear table part are moved forwards into the region of the first guide plate, and this is followed by the next sequence of cuts in the sense described above.
As has been described previously in the prior art according EP-A-0 242 763, the movement of the first guide plate in particular has to be adapted to the conditions for cutting the small stacks. This makes it necessary to provide horizontal mobility of the first guide plate and to ensure that the latter can swivel.
Apart from this, since the first guide plate is a mobile component which has to be installed, it is necessary to position the first guide plate in a defined manner with respect to the front table part or with respect to the partial stacks to be cut, in order to ensure the sequence of movements of the first guide plate which were described above. According to a special feature of the present process, when the first guide plate is installed it is positioned against the partial stacks to be cut. In particular, if when the first guide plate is installed it is positioned against the partial stacks disposed with their front faces in the cutting plane, it is ensured that the guide plate is associated with a defined, fixedly predetermined plane, namely with the cutting plane of the cutter. The coordinates of movement of the first guide plate can thus be fixed with respect to the cutting plane. On the other hand, it is possible to effect a variable association of the contact face of the first guide plate in relation to the cutting plane. This means that the plane of contact of the first guide plate is positioned at an arbitrary spacing from the cutting plane, and the position of the guide plate, particularly its position in relation to the cutting plane, is determined by means of electronics. In particular, the electronics thus determine how far the vertically positioned plane of contact of the guide plate is from the cutting plane, and take this into account during the current cutting process. It is known from the prior art that the positions of machine parts, for example the position of the feed cradle of the cutting machine with respect to the cutting plane, can be determined and represented by means of electronics. The position of the first guide plate can be represented correspondingly.
The transfer of data between the mobile alignment station and the overall control system of the guillotine cutter machine, particularly with respect to the operation of the actuating elements of the mobile alignment station, of the elements for fixing the mobile alignment station to the front table part, and of the elements for determining the position of the mobile alignment station relative to the material to be cut or relative to the cutting plane of the cutters, can also of course be effected by means of remote control, infrared control or the like.
In a further embodiment, after the partial stack has been pushed back on to the rear table part, a mobile alignment station, which receives the first guide plate, is placed on the front table part. After the partial stack has been pushed back on to the rear table part, the mobile alignment station is advantageously moved on to the front table part from an additional table part disposed at the side. In particular, this is effected manually. The receiving planes of the rear table part and of the additional table part can be permanently aligned with each other here, so that when the mobile alignment station is not required it is placed on the additional table part beside the front table part. A certain disadvantage here is that this region is not available to the operator so that he can freely manipulate the material to be cut. Taking this situation into consideration, it is proposed that the additional table part comprises two parallel table planes disposed one above the other, wherein the lower table plane serves to receive the mobile alignment station before it moves on to the front table part and the two table planes of the additional table part can be raised and lowered with respect to the table plane of the front table part. If the mobile alignment station is not required, the additional table part is situated in its lowered position, so that the upper table plane of the additional table part forms a plane with the table plane of the front table part and this region can thus be used for working in without any restriction. If the mobile alignment station is required, the additional table part is raised by an extent such that its lower table plane is aligned with the table plane of the front table part, whereby the mobile alignment station can be transferred without difficulty on to the front table part. If necessary, the additional table part is lowered on to the front table part again whilst the mobile alignment station is in use.
After it has been transferred on to the front table part, the mobile alignment station is preferably attached thereto or to a lateral stop associated with this table part, particularly by means of suction force or magnetic force. It is thereby ensured that the mobile alignment station permanently assumes its desired position in relation to the front table part, which is a prerequisite for the operation of the guide plate.
The material to be cut can be aligned in a simple manner by means of the guide plate of the mobile alignment station. After a cut is made, a displacement of the upper sheets of the material to be cut generally occurs, so that the material can be aligned on the device for feeding the material by moving the first guide plate against the front edge of the material to be cut.
According to a further fundamental embodiment of the process according to the invention, when the first guide plate is installed it is positioned in a defined manner with respect to the front table part. The first guide plate is thus not aligned on the material to be cut, but is aligned on the front table part. In particular, the mobile alignment station which receives the first guide plate can be positioned in different positions on the front table part with respect to the cutting plane of the cutter of the guillotine cutter machine. This takes into account the fact that small stacks have to be cut which have different extents in the direction of feed of the material, and the aim should be to achieve short distances of travel of the guide plate. In this respect, the front table part comprises diverse receivers in planes parallel to the cutting plane of the cutter, for example in three planes, wherein peg-like elements attached to the mobile alignment station can be brought into active communication with said receivers. Since one definitive requirement for the positioning of the mobile alignment station with respect to the front table part is to align the contact face of the first guide plate so that in its initial position it is exactly parallel to the cutting plane of the cutter, provision is made for centring the mobile alignment station on the front table part.
After the partial stacks have been moved forwards, or in the final phase of movement of the partial stacks, the first guide plate is preferably moved in the opposite direction to the direction of feed of the partial stacks, so that the partial stacks are aligned on the feed cradle of the cutting machine. This precise alignment of the partial stacks is a particular prerequisite for a high accuracy of cut when producing the small stacks, particularly when the latter are labels. When the partial stacks are cut, the first guide plate is swivelled so that it is tilted away from the cutter corresponding to the wedge shape of the cutting knife. The electronics preferably detect the downward movement of the cutting knife and control the actuator for swivelling the first guide plate in accordance with the passage of the cutting knife through the partial stacks. Superimposed on this, or subsequently thereto, there is a slight horizontal movement of the first guide plate away from the cutting plane, in order to effect the complete movement of the small stack, which is displaced into the shape of a parallelogram, on to the front table part when the second guide plate is aligned vertically and is completely seated against the rear edge of the front table part. The aforementioned overhang of the small stacks is due to the cutting plane or the cutting strip being disposed in the rear table part slightly offset in relation to the interface between the front and rear table parts. When the second guide plate is disposed vertically, the first guide plate tilts into its vertical position.
The first guide plate can preferably both move horizontally and swivel horizontally. In particular, it can move by differently defined distances. For example, it can be moved by an extent of advance for producing the small stacks, by an extent of advance for compensating for the swivelling movement of the first guide plate, or by an extent of advance for an intermediate cut, particularly in combination with the disposal of the cutting waste through the gap. The guide plate is moved or swivelled in particular by a pneumatically or electrically acting means of force, preferably by means of an electric servomotor.
It is considered to be particularly advantageous if the turned partial stacks are fixed between one or more movable contact placement devices and a fixed lateral contact placement device of the rear table part. This is generally effected before or during the cut in the second direction. A procedure of this type is particularly advantageous when narrow sheets are to be cut, whereby it is ensured that they are aligned exactly parallel to each other and the partial stack associated with the fixed lateral contact placement device is seated flat against the latter.
It is essential that the process according to the invention can be employed for what is termed mixed production. This means that after cutting small stacks, the extent of which is slight in the direction of feed, small stacks have to be cut under some circumstances, the extent of which in the direction of feed is greater. These operations can be put into effect in a simple manner by moving the guide plate of the mobile alignment station or by displacing the mobile alignment station.
Other features of the process according to the invention are presented in the description of the Figures and in the subsidiary claims, where should be remarked that all individual features and all combinations of individual features constitute the essence of the invention.
The process according to the invention is illustrated in the Figures, which comprise a plurality of embodiments of a guillotine cutter machine which operates according to this process, without being limited to the specific process steps described. The Figures are as follows: